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For the four successive transition elements (Cr, Mn, Fe and Co), the stability of +2 oxidiation state will be there in which of the following order?

  • Option 1)

    Mn> Fe> Cr> Co

  • Option 2)

    Fe> Mn> Co> Cr

  • Option 3)

    Co> Mn> Fe> Cr

  • Option 4)

    Cr> Mn> Co> Fe

 

Answers (1)

best_answer

As we learnt in concept no. 10278.

Following is a table showing E^o\:values\:of\: M^{2+}/M

E^o(V)
Cr
Mn
Fe
Co
M^{2+}/M
-0.9
-1.18
-0.44
-0.28

According to the above, the stability order should be:Mn^{2+}> Cr^{2+}> Fe^{2+}> Co^{2+}

But Cr^{2+} is a very strong reducing agent and it gains it's +30.s in aqueous solutions.

2Cr^{2+}_{(aq)}+2H_{(aq)}^{+}\rightarrow 2Cr_{(aq)}^{3+}+H_{2}_{(g)}\upharpoonleft

\therefore the correct order is Mn^{2+}> Fe^{2+}> Cr^{2+}> Co^{2+}

 


Option 1)

Mn> Fe> Cr> Co

This solution is correct 

Option 2)

Fe> Mn> Co> Cr

This solution is incorrect 

Option 3)

Co> Mn> Fe> Cr

This solution is incorrect 

Option 4)

Cr> Mn> Co> Fe

This solution is incorrect 

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Plabita

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